The present invention relates to a method of registering a sheet fed in a feed path through a transport nip, with an image to be transferred thereto, at an image transfer location and from an image support to said sheet. The transport nip, in a registration step, is displaceable transversely of the feed direction between two end positions in order to register a sheet retained in the transport nip with said image.
A method of this kind is known from U.S. Pat. No. 5,219,159. In the method described therein the transport nip is returned, after each registration step, to a middle position situated between the end positions. During this displacement the transport nip cannot receive a following or subsequent sheet, so that the distance between sheets for successive registration must be relatively considerable.
The object of the present invention is to provide a method wherein the distance between the sheets which are to be successively brought into register with an image to be received thereon can be considerably reduced.
According to the present invention, with registration steps taking place successively the transverse displacement of the transport nip is directed initially to a middle position situated between the two end positions, and the sheet and/or image for registration is brought, for the purpose of that registration step, into a transverse position required by a registration step in said initial direction.
Consequently, a sheet can be rapidly and accurately brought into register with an image to be received thereon, in a direction transverse to the feed direction, by means of the transport nip displaceable in the transverse direction, without the transport nip being inoperative for any time between two registration steps in order to reset the transport nip between the transport of two sheets to be successively brought into registration.
The registration can take place without any interruption whatsoever by bringing the sheet into a transverse position required by the registration step in said initial direction, with continuous feed of the sheet to the image transfer location.
If, as an alternative, images to be successively brought into registration with supplied sheets are applied to the image support in the transverse direction at mutually offset positions, then the effect achieved is that at the image transfer location sheet edges do not always need to come into contact with the same part of the image support, and this prevents edge outlining on the image support.